I'm happy with my 507's, but have always wondered how I could possibly improve the soundstage. I was reading DavidMahler's classic headphone comparison blog here and he mentioned that the 507's have a small soundstage, and he gave a higher rating to Stax Sigmas. I've never auditioned Sigmas, but have heard good things about them. I was reading an article about Sigmas that Dolby processing could be an alternative to purchasing Sigmas but details about this are sketchy. I purchased Fidelia awhile back but have rarely used it. Anyway, I'm very unsophisticated about things like that and wondering if there was anything I could purchase (or already have with the Fidelia) that could increase the soundstage of my phones.